Reduce test.dart memory usage

tools/testing/dart/test_suite.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Classes and methods for enumerating and preparing tests.
  *
  * This library includes:
  *
  * - Creating tests by listing all the Dart files in certain directories,
@@ skipping 242 matching lines @@
   //  - update SummaryReport
   //  - handle SKIP/SKIP_BY_DESIGN markers
   //  - test if the selector matches
   // and will enqueue the test (if necessary).
   void enqueueNewTestCase(TestCase testCase) {
     var expectations = testCase.expectedOutcomes;
 
     // Handle sharding based on the original test path (i.e. all multitests
     // of a given original test belong to the same shard)
     int shards = configuration['shards'];
-    if (shards > 1) {
-      int shard = configuration['shard'];
-      var testPath =
-          testCase.info.originTestPath.relativeTo(TestUtils.dartDir);
-      if ("$testPath".hashCode % shards != shard - 1) {
-        return;
-      }
+    if (shards > 1 && testCase.hash % shards != configuration['shard'] - 1) {
+      return;
     }
     // Test if the selector includes this test.
     RegExp pattern = configuration['selectors'][suiteName];
     if (!pattern.hasMatch(testCase.displayName)) {
       return;
     }
 
     // Update Summary report
     if (configuration['report']) {
       SummaryReport.add(expectations);
-      if (testCase.info != null &&
-          testCase.expectCompileError &&
+      if (testCase.expectCompileError &&
           TestUtils.isBrowserRuntime(configuration['runtime']) &&
           new CompilerConfiguration(configuration).hasCompiler) {
         SummaryReport.addCompileErrorSkipTest();
         return;
       }
     }
 
     // Handle skipped tests
     if (expectations.contains(Expectation.SKIP) ||
         expectations.contains(Expectation.SKIP_BY_DESIGN)) {
@@ skipping 1924 matching lines @@
  * $pass tests are expected to pass
  * $failOk tests are expected to fail that we won't fix
  * $fail tests are expected to fail that we should fix
  * $crash tests are expected to crash that we should fix
  * $timeout tests are allowed to timeout
  * $compileErrorSkip tests are skipped on browsers due to compile-time error
 """;
     print(report);
   }
 }